1. Field of the Invention
The present invention is directed to a valve and, in particular, to a valve configured for automatically purging water and other contaminants from a compressed air reservoir.
2. Description of Related Art
Large vehicles, such as buses, trucks, trailers, construction equipment, and recreational vehicles, typically have a pneumatic braking system that runs on compressed air. An air compressor, powered by the vehicle's engine, compresses air that is stored in an air reservoir. Compressing air causes water vapor, oil, and other contaminants to collect in the bottom of the air reservoir. If these contaminants are not removed from the air reservoir on a regular basis, they can damage the air reservoir, enter the braking system and damage the braking components.
A conventional air reservoir typically includes a drain valve that must be manually opened by the vehicle's operator to remove contaminants from the air reservoir. While the drain valve should be opened on a regular basis, such as whenever the engine is turned off, drivers often do not drain the contaminants from the air reservoir on a regular basis, which can damage the air reservoir and braking system.
Automatic purge valves have been developed to automatically purge the contaminants from an air reservoir based upon the occurrence of a specific event, such as an air compressor turning on/off, an ignition turning on/off, and a periodic timer expiring. Each of these types of automatic purge valves requires electrical power or a connection to the air compressor to activate the valve. These valves cannot be used when the air reservoir does not have access to electrical power or the air compressor, such as when the air reservoir is mounted on a trailer. There are also automatic purge valves, such as described in U.S. Pat. No. 5,205,315 to Margerum and U.S. Pat. No. 5,865,208 to Chovan, that open when a vehicle's parking brake is engaged to automatically drain moisture from the air reservoir when the vehicle is parked. These valves, however, may be fairly noisy when operated.